For seven years since it was planted, the puya has been a mass of serrated fronds resembling an overgrown aloe vera.

But earlier this year a flower spear started rising out of the foliage and now stands almost four metres tall.

The top of the spear is covered with bright yellow flowers and green spikes that local honeyeaters use as a perch to collect nectar from the yellow blooms.

Warrnambool Botanic Garden curator John Sheely said it was amazing the plant had flowered at all.

"This puya is from the arid hillsides of Chile, so with our cool, wet climate we are lucky to get a flower," he said.

"The flower spike only appeared in September, so it has really rocketed."

Mr Sheely said he hoped the flower would keep blooming for the next month or so, but it was at its peak right now.

He said it was one of five varieties of puya he had planted since becoming curator in 2007, but the first to produce such an impressive flower spike.

He said he hoped to keep adding striking plants to the heritage-listed gardens, designed by William Guilfoyle in 1879.

"He was all about bold foliage and contrasting foliage, so we can use some of those exotic species," Mr Sheely said.

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